The objective is the development of an econometric model of the labor market behavior of retirement age males. The ultimate model will integrate market demand considerations for the work effort of older males into a supply model which emphasizes health constraints on behavior. The resulting structural model should provide a useful tool for the prediction of changes in older male labor market activity in response to government controlled parameters (Social Security benefits, modifications in mandatory retirement restrictions, etc.) as well as industrial conditions (trends in industry structure and labor productivity and cyclical variations in industrial unemployment). The supply function for retirement age workers will focus on the critical interaction of health status, non-employment income opportunities, including Social Security benefits and private pension rights; and labor market possibilities. The demand for retirement age labor will be structured as a function of industrial characteristics which may affect the hierarchical structure of the firm (e.g., firm size), resulting in relative rigid rules (explicit or implicit) affecting older male demand. The determinants of pension policies, mandatory retirement rules, and wage adjustments (for those who remain employed), will receive the principal empirical focus since they are likely to strongly alter the individual's supply response.